This invention relates to the treatment of hydrocarbon gas. In one of its aspects this invention relates to a method for reducing the CO.sub.2 content of a hydrocarbon gas-CO.sub.2 mixture to produce hydrocarbon gas having a sufficient BTU content for use as fuel. In another of its aspects this invention relates to a method for separating CO.sub.2 and hydrocarbon gas from a mixture thereof. In yet another of its aspects this invention relates to the recovering of a CO.sub.2 enriched product gas from a CO.sub.2 -hydrocarbon gas mixture.
Hydrocarbon gas streams are produced from underground formations with the hydrocarbon gas containing CO.sub.2 in amounts from a trace up to about 98% of the total. A hydrocarbon gas containing carbon dioxide may be the natural product from the formation or the mixture of hydrocarbon gas and CO.sub.2 can be the product of improved oil recovery projects in which CO.sub.2 is injected into a reservoir to displace oil. While relatively small amounts of CO.sub.2 in a hydrocarbon gas stream are not harmful, relatively large amounts of CO.sub.2 sufficiently reduce the BTU content of the mixture so that it is not useful as a fuel gas.
It is therefore an object of this invention to provide a method for treating a mixture of hydrocarbon gas and carbon dioxide sufficiently to reduce the CO.sub.2 content to provide a resulting mixture that is useful as a fuel. It is another object of this invention to provide a method for separating hydrocarbon gas from a mixture of hydrocarbon gas and carbon dioxide to produce a stream of increased carbon dioxide content.
Other aspects, objects, and the various advantages of this invention will become apparent upon reading the specification and the appended claims.